Willowsia nigromaculata ( Lubbock, 1873 )

Cipola, Nikolas G. & Katz, Aron D., 2021, Morphological and molecular analysis of Willowsia nigromaculata (Collembola, Entomobryidae, Entomobryinae) reveals a new cryptic species from the United States, European Journal of Taxonomy 739 (1), pp. 92-116 : 97-104

Willowsia nigromaculata ( Lubbock, 1873)

Figs 2–7 , 10–11 ; Tables 2–3

Seira nigromaculata Lubbock 1873: 146 , Great Britain (orig. descr.).

Willowsia nigromaculata – Shoebotham 1917: 432 (comb.). — Zhang et al. 2011 (descr.).

Type species

Seira nigromaculata Lubbock, 1873 .

Diagnosis

Body with pigments laterally on head to Abd III, and spots on Abd IV, femur and tibiotarsus ( Fig. 2 ); head mac S0 absent, Ps3 mes and Ps5 mac present; sublobal plate with 2 inner appendages ( Fig. 5E ); Th II–Abd IV formula with 9,8|3,3,3+7,7+14 mac, p2a rarely present on Th III ( Fig. 6A–C ); manubrium dorsally with 7 lateral chaetae abruptly acuminate at the tip, manubrial plate with 3–4 chaetae, 1 mac ( Fig. 7G–H ).

Material examined

FRANCE • 2 ♂♂, 5 ♀♀, 1 juvenile on slides, 7 specimens in alcohol; Paris, National Museum of Natural History, Department de Systematique et Évolution; 48°50′30.0″ N, 02°21′33.1″ E; in laboratory benchtop; 1 Jun. 2016; VD Tarli leg.; INPA .

Description

LENGTH. Total length (head + trunk) of specimens 1.51–1.85 mm (n = 3). Specimens pale yellowish white with violet pigments on Ant II to Ant IV, head laterally, margins of Th II–Abd II, Abd III with one transverse band that expands laterally, Abd IV dorsally with one irregular lateral spot, irregular spots on

dorsoventral plate and posterior border; distal half of Abd V to VI, distal femur and tibiotarsus medially; eyepatches black ( Fig. 2 ).

HEAD. Antennal ratio as I: II: III: IV = 1: 1.83–2.00 1.68–2.12: 1.81–2.36 (n = 3). Ant IV not annulated, with apical bulb bilobed and sometimes retraticle. Five interocular chaetae (q, v, p, r, t); head dorsal macrochaetotaxy ( Fig. 5B ) with 5 ‘An’ (An1a–3), 4 ‘A’ (A0, A2–3, A5), 3 ‘M’ (M1–2, M4), 6 ‘S’ (S2– 6), 1 ‘Ps’ (Ps5), 5 ‘Pa’ (Pa1–5), 2 ‘Pm’ (Pm1, Pm3), 5 ‘Pp’ (Pp1–5), and 2 ‘Pe’ (Pe2–3) mac; An2a?, A1, A4? mic present. Maxillary palp with t.a. smooth and b.c. weakly striated, thicker and 1.12 longer than t.a.; sublobal plate with 2 inner (sb.2–3) and 1 outer (sb.4) smooth appendages, sb.2 smaller and sb.4 minute ( Fig. 5E ). Ventral chaetotaxy with about 68 ciliate chaetae, 36 thin of differents sizes, 31 normal and subequal in length and 1 b.c., cephalic groove with 6 chaetae; postlabial formula with 4 (G1–4), 4 (X, X2–4), 4 (H2–4), 4 (J1–4), 2 (X’, X4’) chaetae ( Fig. 5G ).

THORAX CHAETOTAXY ( Fig. 6A ). Th II, anterior collar with numerous chaetae; a, m and p series with 1 (a5), 1 (m4) and 7 (p1–5) mac, respectively. Th III, a, m and p series with 2 (a4, a6), 4 (m5–7) and 5–6 (p1–3, p5–6) mac, respectively, p2a mac rarely present; laterally numerous mes. Ratio Th II: III = 1.48–1.30: 1 (n=3).

ABDOMEN CHAETOTAXY ( Fig. 6B–F ). Abd I, m series with 3 mac (m2–4) subequal in length. Abd II, a and m series with 1 (a2) and 3 (m3–3e, m5) mac, respectively; a5 and m2 bothriotricha with 9 and 6 accessory chaetae, respectively ( Figs 3C , 6D ). Abd III, a, m and p series with 3 (a2–3, a7), 4 (m3, am6, pm6, m7) and 3 (p6, p7–7i) mac, respectively; m2 bothriotrichum with 3 accessory chaetae and a5 and m5 bothriotricha with 15 accessory chaetae between them ( Fig. 6E ). Abd IV, A to T series with 7 mac (A3–4, A6, B4–6, C1) and E to Fe series with 14 mac (E2a–3, E4p, F1–3p, Fe3–5); T2 and T4 bothriotricha with 2 mic and 8 accessory chaetae between them ( Fig. 6F ); 2 sens type I (as, ps), 4 sens type II, and 13 posterior chaetae of different sizes. Abd V a, m, pa and p series with 1 (a5), 4 (m2–3, m5–5e), 1 (p6ai) and 5 (p1, p3–6) mac, respectively. Ratio Abd III: IV = 1: 3.61–4.14 (n= 3).

LEGS. Subcoxa I with 3 chaetae and 2 psp; subcoxa II with an anterior row of 7 chaetae and about 16 anterior chaetae, posterior row of 3 chaetae and 2 psp; subcoxa III with one row of 7 chaetae, about 16 anterior chaetae and 2 posterior psp ( Fig. 7A–C ). Trochanteral organ with 12–16 spine-like chaetae ( Fig. 7D ). Ratio unguis: unguiculus = 1: 0.52. Tibiotarsal smooth chaeta 1.09 the length of unguiculus; tenent hairs 0.97 the length of unguis.

COLLOPHORE. Anterior side with about 20 chaetae, 5 mac and 3 mes ciliate and abruptly acuminate at the tip, and 13 thin chaetae weakly ciliate; posterior side with 8 chaetae (1 unpaired) weakly ciliate and 2 distally thicker; lateral flap with 3 smooth chaetae and 9 chaetae weakly ciliate ( Fig. 7F ).

FURCULA. Manubrium ventrally with 4 subapical chaetae of the same length and 14–16 apical chaetae, 6 inner chaetae smaller, others subequal ( Figs 4C , 7I ); dorsally with one lateral row of 7 ciliate chaetae abruptly acuminate at the tip, 3 mac and 4 mes (1 basal and 1 antero-subapical); manubrial plate with 3–4 ciliate chaetae of different sizes (1 mac abruptly acuminate at the tip) and 2 psp ( Figs 4A–B , 7G–H ).

DNA Barcodes

GenBank KY468311 ; Teillet, France ( Ding et al. 2018). GenBank MG032239 , MG036766 , MG039377 ; Toronto, Canada ( deWaard et al. 2019).

Figures

Fig. 2. Willowsia nigromaculata (Lubbock, 1873), habitus. A. Lateral view. B. Dorsal view. Scale bars: 0.5 mm.

Fig. 3. Scanning electron microscopy of Willowsia nigromaculata (Lubbock, 1873). A. Scale apically pointed of Abd IV. B. Tergal microchaeta basally smooth and with ramification on distal half. C. Bothriotrichal complex of Abd II, m2 is bothriotrichum. D. Distal tibiotarsus and empodial complex I (posterior side), black arrow indicates pretarsal chaeta and white arrows indicates unguiculus lamellae. E. Distal tibiotarsus and empodial complex II (outer side), white arrow indicates unpaired basomedian tooth and black arrows indicates paired basolateral teeth of the unguis. F. Distal dens and mucro (lateral side). Abbreviations: see Material and methods. Scale bars: A, C–F = 5 μm; B = 2 μm.

Fig. 4.Optical microscope photography of Willowsia nigromaculata(Lubbock, 1873). A. Furcula (dorsal view). B. Manubrium (dorsal view), arrows indicate mac and mes suddenly acuminate, respectively. C. Manubrium and proximal dentes (ventral view), arrow indicate subapical chaetae. Scale bars: A, C =100 μm; B = 50 μm.

Fig. 5. Willowsia nigromaculata (Lubbock, 1873), head (left side). A. Ant III apical organ. B. Cephalic dorsal chaetotaxy.C. Chaetotaxy of clypeus, prelabrum and labrum. D. Labral papillae. E. Maxillary outer lobe. F. Papilla E of labial palp (ventral view). G. Basomedian and basolateral labial fields and complete postlabial chaetotaxy. Abbreviations: see Material and methods.

Fig. 6. Willowsia nigromaculata (Lubbock, 1873), dorsal chaetotaxy (left side). A. Th II–III. B. Abd I–III. C. Abd IV–V. D–F. Bothriotrichal complex. D. Abd II. E. Abd III. F. Abd IV. Abbreviations: see Material and methods.

Fig. 7. Willowsia nigromaculata (Lubbock, 1873). A. Subcoxa I. B. Subcoxa II. C. Subcoxa III (lateral view). D. Trochanteral organ. E. Distal tibiotarsus and empodial complex III (posterior view). F. Collophore chaetotaxy (lateral view). G. Manubrium dorsal chaetotaxy. H. Manubrial plate. I. Subapical and apical chaetotaxy of ventral manubrium. J. Mucro (lateral view). Abbreviations: see Material and methods.

Fig. 10. COI p-distance (uncorrected) frequency histogram (in gray) and boxplots comparing p-distances between A. Entomobryinae species. B. Entomobryinae sister species. C. Willowsia nigromaculata (Lubbock, 1873) (France and Toronto, Canada) and W. neonigromaculata sp. nov (USA and Brockville, Canada) clades (inter-specific distances). D. Lineages within the same W. nigromaculata or W. neonigromaculata sp. nov. clade (intra-specific distances).

Fig.11.BayesianconsensustreeestimatedwithMrBayesforEntomobryinae,includingthecladecomprised of Willowsia nigromaculata (Lubbock, 1873) from France and Canada and W. neonigromaculata sp. nov. from the USA and Canada (highlighted). MrBayes and BEAST posterior probabilities and RAxML bootstraps are indicated at each node, respectively. The ingroup node constrained as monophyletic for all phylogenetic analyses is indicated with an asterisk (*).